---
title: "Definition of transition elements"
subject: "Engineering Chemistry"
chapter: 5
key: "semester_2/engineering_chemistry:tm-definition"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/tm-definition
site: BCT Engineering
---

# Definition of transition elements

Engineering Chemistry · Chapter 5: 3-d Transition Elements and their Applications

- Asked in: 2070 Magh, 1 marks
- Video: [Transition Metals | Periodic table | Chemistry | Khan Academy](https://www.youtube.com/watch?v=kCM2mSb4qIU) — Khan Academy Organic Chemistry
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/tm-definition
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-5

## Question

What are transition elements?

## Short answer

Transition elements are d-block elements whose atoms or at least one common ion have an incompletely filled d subshell. Examples include Fe (3d⁶4s²) and Cu²⁺ (3d⁹).

## Answer

Transition elements are the d-block elements whose atoms, or at least one of their common ions, have an incompletely filled d subshell (for example Fe: 3d⁶ 4s²; Cu²⁺: 3d⁹).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Transition elements are those whose atoms or common ions have
   A. a completely empty s subshell
   B. only p electrons
   C. an incompletely filled d subshell
   D. a noble gas core only
   Answer: C. Partly filled d subshell in the atom or an ion defines them. (Key point: Definition)

2. Why is copper a transition element though Cu is 3d10 4s1?
   A. Cu+ is 3d0
   B. Cu2+ is 3d10
   C. Cu has no d electrons
   D. Cu2+ is 3d9, an incomplete d subshell
   Answer: D. Cu2+ has 3d9. (Key point: Example in an ion)

3. What is the outer electronic configuration of Fe?
   A. 3d6 4s2
   B. 3d8 4s0
   C. 3d5 4s2
   D. 3d10 4s2
   Answer: A. Fe: [Ar] 3d6 4s2. (Key point: Fe configuration)

## Related in Engineering Chemistry

- [Complex formation by transition elements](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Acomplex-formation-tm) — Engineering Chemistry, chapter 5, asked 11×
- [Why d-block elements are called transition](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awhy-transition-elements) — Engineering Chemistry, chapter 5, asked 2×
- [Transition elements; first series configuration](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Awhy-transition-elements-typical) — Engineering Chemistry, chapter 5
- [Transition elements; configuration; paramagnetism](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Atm-config-paramagnetism) — Engineering Chemistry, chapter 5
- [Transition elements; non-typical 3d element](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Atm-not-typical) — Engineering Chemistry, chapter 5
- [General outer electronic configuration of transition elements](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Atm-general-config) — Engineering Chemistry, chapter 5

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